• 한국지하수토양환경학회지:지하수토양환경
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• 제14권3호
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• pp.40-46
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• 2009

독립영양 황탈질 미생물 Thiobacillus denitrificans를 이용한 질산염 오염지하수 정화 기술을 개발하고자, 3열의 관정형 반응벽체(길이 $\times$ 너비 $\times$ 깊이 = $3m\;{\times}\;4\;m\;{\times}\;2\;m$)를 한국농어촌공사 수리시험장(길이 $\times$ 너비 $\times$ 깊이 = $8m\;{\times}\;4\;m\;{\times}\;2\;m$)에 설치하고 현장적용성을 검토하였다. 전자공여체로 총 80 kg의 황입자를, 탈질미생물로 Thiobacillus denitrificans를 준비하였다. 황입자 표면에 Thiobacillus denitrificans를 부착하는 1톤 용량 물통 실험에서, Thiobacillus denitrificans는 질산염 농도 375 mg/L(6.1 mM)의 오염수를 11일 경과 후 ~12% (0.7 mM), 18일 경과 후 ~24%(1.3 mM), 32일 경과 후 ~45%(2.4 mM), 그리고 부착 종료 시(60일)까지 ~52%(2.8 mM)를 제거하며 황입자 표면에 성공적으로 부착 증식하였다. 이후, Thiobacillus denitrificans가 부착된 황입자를 3열의 관정형 반응벽체(각 열 간격 1 m)에 주입하여 황탈질 미생물 관정형 반응벽체를 설치하였다. 초기 질산염 농도 평균 181 mg/L 인 인공오염지하수에 대하여 28일 간 1차 정화실험을 실시하였고, 평균 281 mg/L 인 인공오염지하수에 대하여 14일 간 2차 정화실험을 실시하였다. 1차 실험의 인공오염지하수(2.9 mM)는 1열 반응 후 ~2%(0.06 mM), 2열 반응 후 ~9%(0.27 mM), 3열 반응 후 ~15%(0.44 mM)의 질산염이 제거되었다. 2차 실험의 인공오염지하수(4.5 mM)는 1열 반응 후 ~1%(0.02 mM), 2열 반응 후 ~6%(0.27 mM), 3열 반응 후 ~8%(0.37 mM)가 제거되었다. 실험 기간 중 인공오염지하수의 주입용량은 $1.24\;m^3/d$, 유속은 0.44 m/d를 유지하였고, pH는 6.7~8.3, DO는 0.9~2.8 mg/L 범위로 큰 변화가 없었다. 본 관정형 반응벽체 실험의 낮은 정화효율의 원인은 인공오염지하수에 대한 Thiobacillus denitrificans의 탈질 소요 시간 부족, 관정형 반응벽체의 개별 관정사이로 빠져나가는 인공오염지하수체, 그리고 질산염 환원효소의 활성 및 생성을 억제시키는 용존산소의 상대적으로 높은 농도 때문으로 추정된다. 황탈질 관정형 반응벽체의 현장적용시에는 탈질반응에 필요한 체류시간, 관정형 반응벽체의 개수 및 간격, 그리고 용존산소 농도 등 해당 오염부지의 고유 특성을 고려한 설계가 필요하다.

• Journal of Nutrition and Health
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• 제32권7호
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• pp.802-811
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• 1999

The purposes of this study were to 1) examine the dietary patterns of fatty acids and the fatty acid composition in serum, 2) determine selenium (Se) concentrations, and 3) investigate how serum fatty acid compositon affects serum levels of Se in Korean elementary school children. The subjects consisted of 168 school children(82 boys & 86 girls) belonging to 1st through 6th grades, and their dietary assessment was evaluated. The serum fatty acid composition was analyzed by GLC, and the ICP/MS method was employed to measure serum Se concentration. Total average intake of PUFA, MUFA and SFA were 10.5g, 12.7g, 11.2g respectively. Total average dietary P/M/S ratio was 1.10/1.18/1.0. The average intake of $\omega$3 fatty acids and $\omega$6 fatty acids were 1.33g, 9.19g, respectively. The $\omega$6/$\omega$3ratio was 14.2 which is higher than the recommended range. In serum fatty acid composition, PUFA, MUFA, SFA were 40.6%, 28.1% and 31.6% respectively. The average $\omega$3 fatty acid composition was 3.80%, and the mean value of $\omega$6 series was 36.8%. The M/S ratio of girls was significantly higher than boy's in fatty acids intake and in serum composition. Mean Se concentration of total subjects was 416.7ug/l and it was significantly higher in the lower grades(1st-3rd)than in the upper grades(4th~6th, p<0.05). Although the mean serum Se concentration was negatively correlated with PUFA composition in total boys and girls, it was not significant. Serum Se concentration was negatively correlated with P/S ratio and C24:1 concentration(p<0.05). In addition, serum composition of $\omega$6 PUFA and C24:1 showed negative correlations with serum Se in only lower grades girl(1st~3rd), and further studies are needed to clarify in these phenomena. In conclusion, the mean serum Se concentration was significantly lower in upper grades (4th~6th)than in lower grades(1st~3rd) of elementary school children and was negatively correlated with P/S ratio of serum fatty acids. More detailed studies on relationship between Se and fatty acids are required.

• Smart Structures and Systems
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• 제31권1호
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• pp.1-11
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• 2023

Assessment of the compressive strength of concrete plays a major role during formwork removal and in the prestressing process. In concrete, temperature changes occur due to hydration which is an influencing factor that decides the compressive strength of concrete. Many methods are available to find the compressive strength of concrete, but the maturity method has the advantage of prognosticating strength without destruction. The temperature-time factor is found using a LM35 temperature sensor through the IoT technique. An experimental investigation was carried out with 56 concrete cubes, where 35 cubes were for obtaining the compressive strength of concrete using a universal testing machine while 21 concrete cubes monitored concrete's temperature by embedding a temperature sensor in each grade of M25, M30, M35, and M40 concrete. The mathematical prediction model equation was developed based on the temperature-time factor during the early age compressive strength on the 1^st, 2^nd, 3^rd and 7^th days in the M25, M30, M35, and M40 grades of concrete with their temperature. The 14^th, 21^st and 28^th day's compressive strength was predicted with the mathematical predicted equation and compared with conventional results which fall within a 2% difference. The compressive strength of concrete at any desired age (day) before reaching 28 days results in the discovery of the prediction coefficient. Comparative analysis of the results found by the predicted mathematical model show that, it was very close to the results of the conventional method.

• 한국대기환경학회지
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• 제2권3호
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• pp.57-63
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• 1986

Atmospheric particulate matter (A.P.M.) was collected on quartz fiber filters from March 1985 to May 1986 according to particle size using Andersen high-volume air sampler, and 6 heavy metals (Fe, Mn, Cu, Ni, Zn, Pb) in these particulates were analyzed by atomic absorption spectrophotometry. The arithmetic mean concentration of A.P.M. was 195.57$\mug/m^3$. The arithmetic mean concentrations of 6 metals (Fe, Mn, Cu, Ni, Zn and Pb) were 3385.04, 1451.67, 897.94, 159.68, 127.14 and 59.49 $ng/m^3$ respectively. The order of heavy metals contributing to A.P.M. was as follows: Fe > Zn > Pb > Cu > Mn > Ni. These heavy metals were devided into 3 groups according to their particle size distribution. The contents of heavy metals belonging to the 1st group (Fe, Mn) were increased with the particle size. On the contrary, the content of Pb belonging to the 2nd group (Pb) was increased with the decrease in the particle size. The heavy metal contents in the 3rd group (Ni, Cu, Zn) were lowest in the particle size range of 2.0-3.3 $\mum$ compared with particles larger or smaller tha this range. The seasonal variation of heavy metal concentration were as follows: Fe and Mn contents were highest in spring, but Ni and Pb contents were highest in winter. Statistical analysis showed that there was a significant correlation between A.P.M. and Fe in coarse particles, meanwhile between A.P.M. and Pb in the case of fine particles.

• 대한소아치과학회지
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• 제44권2호
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• pp.180-187
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• 2017

본 연구는 접착층을 통한 자이오머(Beautifil Injectable)와 컴포머($Dyract^{(R)}$ XP)의 불소 유리를 직접적으로 평가하고 비교하였다. 자이오머와 컴포머 그리고 불소를 함유하지 않은 복합레진의 원통형 시편을 각각 20개씩 제작하였다. 20개 중 10개의 시편은 접착제(Scotchbond Multi-Purpose)를 균일하게 도포하였다. 각 시편은 2 mL 탈이온수에 넣어 $37^{\circ}C$에서 보관하였으며 1, 3, 7, 14, 21, 28일째 유리된 불소를 측정하였다. 접착제를 적용한 추가적인 시편을 제작하여 주사전자현미경으로 접착제가 균일하게 도포되었는지 확인하였다. 자이오머와 컴포머에 접착제를 도포한 군은 3일째까지 불소가 검출되지 않았으나 7일째부터는 불소가 검출되었다. 접착제는 불소의 유리를 완전히 차단하지 못하였으며, 접착제를 투과하는 자이오머와 컴포머의 불소 유리량은 유의하게 감소하였다(p < 0.05). 불소의 유리량 감소는 컴포머보다 자이오머에서 더 현저했다.

• 한국토양비료학회지
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• 제48권5호
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• pp.522-527
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• 2015

Decision of available soil depth based on soil physical and hydraulic properties for the $3^{rd}$ Landscape Vegetation Project in the Incheon International Airport was attempted. The soil samples were collected from the 8 sites at different depths, 0-20 and 20-60cm, for the three project fields, A, B, and C area. Physical and chemical properties including particle size distribution, organic matter content and electrical conductivity were analyzed. Hydrological properties including bulk density and water holding capacity at different water potential, -6 kPa, -10 kPa, -33 kPa, and -1500 kPa were calculated by SPAW model of Saxton and Rawls (2006), and air entry value was calculated by Campbell model (1985). Based on physical and hydrological limitation, feasibility and design criteria of soil depth for vegetation and landfill were recommended. Since the soil salinity of the soil in area A area was $19.18dS\;m^{-1}$ in top soil and $22.27dS\;m^{-1}$ in deep soil, respectively, landscape vegetation without amendment would not be possible on this area. Available soil depth required for vegetation was 2.51 m that would secure root zone water holding capacity, capillary fringe, and porosity. Available soil depth required for landscape vegetation of the B area soil was 1.51 m including capillary fringe 0.14 m and available depth for 10% porosity 1.35 m. The soils in this area were feasible for landscape vegetation. The soil in area C was feasible for bottom fill purpose only due to low water holding capacity.

• 대한지역사회영양학회지
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• 제4권1호
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• pp.20-29
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• 1999

This study was done to investigate the nutrient intakes and plasma biochemcial indices in 68 female college students according to their skin types. Nutrient intakes were investigated by quick estimation. The plasma TG and total cholesterol levels were measured by the Spotchem sp-4410. The plasma levels of retinol and $\alpha$-tocopherol were measured by HPLC. In addition, the activities of antioxidant defense enzymes such as plasma glutathione peroxidase(GSH-Px) and glutathione reductase(GHS-Rd) were determined. All data were statistically analyzed by SAS PC package program. The results of this study were as follows : The average age, height, weight, BMI, systolic blood pressure and diastolic blood pressure ofthe subjects were $20.9{\pm}1.9yr, 160.7{\pm}4.3cm, 53.0{\pm}7.1kg, 20.5{\pm}2.4kg/m^2, 105.3{\pm}11.5mmHg and 70.6{\pm}7.7mmHg$, respectively. Ten students(14.7%) had normal skin type, 19 students(27.9%) had dry skin type, 11 students(16.2%) had oily skin type, 17 students(25.0%) had acne and 11 students(16.2%) had mixed skin type. The intakes of energy and fats in oily skin group were significantly higher(p<0.05) than those of the dry skin group, but vitamin C intake in the mixed skin group was significantly higher(p<0.05) than those of the dry skin group, but vitamin C intake in the mixed skin group was significantly lower(p<0.05) than that in other skin types. The intakes of other nutrients were not significantly different among skin types. The analysis of lipids showed that the plasma total-cholesterol level of mixed skin group was significantly lower(p<0.05) than that of the oily skin group, whereas other lipid levels were not significantly different. The other parameters such as retinol, $\alpha$-tocopherol, GSH-Px and GSH-Rd of plasma were not significantly different among skin types. Overall results indicate that dietary intake pattern may influence skin type and thereby some blood biochemical indices can be different by skin types.

• 지구물리와물리탐사
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• 제14권4호
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• pp.316-323
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• 2011

대형 고분의 발굴 조사를 위한 전기비저항 탐사법의 적용 가능성을 시험하기 위하여, 나주 복암리 3호분에 대하여 3차원 전기비저항 탐사를 수행하였다. 높은 해상도의 지하구조 영상을 얻기 위해서는 고분의 정확한 지형 구조 및 전극 위치에 대한 정보 획득이 필수적이다. 이에 따라 문화재 발굴 조사에서 사용하는 방법인 실을 이용한 구획설정법을 응용하여 전극을 설치하였다. 탐사 자료는, 전극 간격은 2 m, 측선 간격은 1 m로 하여 얻었으며, 각 탐사 측선은 상대적으로 1 m 엇갈리게 배열함으로써 전체적으로 고분에 대하여 1 m ${\times}$ 1m 크기의 격자망으로 구성하였다. 탐사 자료에 대하여 3차원 전기비저항 영상화를 수행하고 이를 기존의 발굴 조사 결과와 대비하였으며, 이로부터 확인된 매장 유구 분포와 전기비저항 영상이 매우 잘 일치함을 확인하였다. 이 연구를 통하여 대형 고분에서 매장 유구를 조사할 때 3차원 전기비저항 영상화 기술이 매우 유용함을 밝혔다.

• Journal of Ecology and Environment
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• 제44권2호
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• pp.72-80
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• 2020

Background: Antibiotics are widely used to treat animals from infections. After fertilizing, antibacterials can remain in the soil while adversely affecting the soil microorganisms. The concentration of oxytetracycline (OTC) in the soil and its effect on the soil microbial community was assessed. To assess the impact of OTC on the soil microbial community, it was added to the soil at concentrations of 50, 150, and 300 mg kg^-1 and incubated for 35 days. Results: The concentration of OTC added to the soil decreased from 150 to 7.6 mg kg^-1 during 30 days of incubation, as revealed by LC-MS. The deviations from the control values in the level of substrate-induced respiration on the 5th day of the experiment were, on average, 26, 68, and 90%, with OTC concentrations at 50, 150, and 300 mg kg^-1, respectively. In samples with 150 and 300 mg kg^-1 of OTC, the number of bacteria from the 3rd to 14th day was 2-3 orders of magnitude lower than in the control. The addition of OTC did not affect the fungal counts in samples except on the 7th and 14th days for the 150 and 300 mg kg^-1 contaminated samples. Genes tet(M) and tet(X) were found in samples containing 50, 150, and 300 mg kg^-1 OTC, with no significant differences in the number of copies of tet(M) and tet(X) genes from the OTC concentration. Conclusions: Our results showed that even after a decrease in antibiotic availability, its influence on the soil microbial community remains.

• 한국식품과학회지
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• 제37권6호
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• pp.861-865
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• 2005

본 연구는 일반적으로 사용되고 있는 vitamin C 분석방법인 2,4-dinitrophenylhydrazine(DNP), indophenol, 그리고 HPLC법을 이용하여 시판중인 다양한 제품을 이용하여 보존조건($10^{\circ}C,\;20^{\circ}C$)에 따른 vitamin C 함량을 세 가지 방법으로 비교 검토함으로서 가장 이상적인 분석방법을 조사하였다. $10^{\circ}C$ 보존시 요쿠르트 A 제품에서의 vitamin C 변화 추세를 살펴보면, DNP법은 초기와 말기 TAA 함량이 각자 26.7과 22.8mg/100mL로 측정되었으나, 저장 3일째와 10일째에 오히려 증가하는 현상을 보였으며, 또만 indophenol법은 초기와 말기에 각각 28.6과 9.5mg/100mL로, HPLC법은 30.5와 14.6mg/100mL로 확인되었다. 그리고 본 실험에서는 indophenol법과 HPLC법은 일정한 감소 추세를 보였다. 따라서, 가장 이상적인 vitamin C 분석 방법은 HPLC법이며, 저장 초기에 간단하게 vitamin C 함량을 측정할 경우에는 indophenol법을 이용하여도 신뢰할 수 있는 결과를 얻을 수 있는 것으로 사료된다.